the one you can afford
don't confuse a power "conditioner' with a transformer or an Uninterupptible Power Supply - think of it as a standard power strip that fits nicely into your rack. I chose a model with pull out lights and a dimmer control - handy when your at a gig, very low lighting, and you need to see something on your FX unit that the LCD doesn't report
I have a Furman something-or-other 8 way in one rack and a Chandler something-or-other 12 way in another rack. Both have lights with dimmer control. I have Tripp Lite UPS's to plug those into. The UPS's cannot keep me going during an extended power failure but they do allow me to perform a "gracefu"' shutdown when a failure occurs
there's a lot of hype about power conditioners - most of it is BS